1. Field of the Invention
The invention relates to arthroscopic systems and to couplings for quickly connecting and disconnecting coaxial sockets and associated plugs. More particularly, the invention relates to an arthroscopic sheath having a quick coupling socket for use with a suitably adapted plug member associated with a tool to be received in the sheath.
2. Description of the Prior Art
As will be noted below, arthroscopy is an established medical procedure. Existing arthroscopes, however, are in need of improvements in efficiency of operation and it is such improvements with which this invention is concerned.
As will be explained below, it is desirable to utilize "quick couplings" in arthroscopic applications. Quick connecting couplings (joining male plugs and female sockets) have been known for quite some time in hydraulic and fluidic applications, althoug all known prior art quick coupling devices are, for various reasons, unsuitable for arthroscopic purposes. This invention relates in part to improvements in quick connect couplings to provide couplings suitable for arthroscopic applications as well as for conventional uses of such devices. A brief description of arthroscopy will aid in understanding the invention.
An arthroscope is a miniaturized tubular optical device which allows a surgeon to observe internal areas of a patient, up to several inches inside the body, and to perform both inspection and surgery through an incision of only about 1/4 inch. Fiber optic means are provided to illuminate the operating area inside the body. Arthroscopic devices and the associated surgical methodology have been developed primarily for the purpose of arthroscopic knee surgery, although it is becoming increasingly commonplace to use this minimally traumatic procedure on other joints and areas of the body.
To use the arthroscope the surgeon typically makes three small (1/4") incisions: one for observation via the arthroscope, a second for the surgical cutting devices and a third for removing the irrigating saline solution used to keep the knee (or other area being operated upon) distended and to flush away blood and other debris. Next, a sharp obturator in inserted and locked into a tubular arthroscope sheath to effectively fill up the entire inside of the sheath and form essentially a solid rod with a sharp, pointed end that extends beyond the sheath. This combination sheath/obturator enables forced insertion of the arthroscopic sheath through the incision into the area to be examined. After the sheath is positioned, the sharp obturator is removed and the arthroscope inserted and locked to the sheath. It is this locking mechanism, further discussed below, with which this invention is in part concerned.
The sheath is a tube, several inches long, which forms a guide and holder for the arthroscope and various tools and remains in place throughout the procedure. The arthroscope is basically an eyepiece which may be viewed directly or, alternatively, a miniature camera may be attached to or replace the eyepiece. Fibre optic means are provided, coaxially surrounding the viewing optics, in order to illuminate the operating area. The sheath may also be provided with an irrigating fluid port through which saline solution is pumped into or out of the space between the sheath and arthroscope tube and ultimately to and from the operating area. The saline is prevented from passing out of the sheath past the eyepiece by an arrangement of O-rings. In known prior art arthroscopic sheaths coaxial alignment is not always precise, resulting in the cylindrical space between the arthroscope and the sheath not being uniform throughout the length of the sheath because of improper alignment of the arthroscope within the sheath. This affects the "feel" and operation of the arthroscope. "Play" between the distal end of the scope of the sheath compromises the "feel" of this instrument to the surgeon. Also, the volume and velocity of fluid flowing in the tube is not necessarily annularly uniform. Consequently, if flow happens to be reduced to the viewing side of the arthroscope, there is a possibility that the view will be impaired by debris. Therefore, there is a need for an arthroscopic device capable of avoiding this deficiency. As will be shown below, the invention provides such a device by enabling the centering of the arthroscope within the sheath and by enabling increased fluid flow due to modifications to the irrigation holes.
In the course of the surgery, the arthroscope may be changed or removed from the sheath to allow rapid flushing or to move the sheath to one of the other holes. The scopes utilized may have a variety of different viewing angles from straight ahead to approximately a right angle and during the surgery a variety of scopes may be used. An average of approximately four devices are routinely inserted into the sheath and removed, perhaps many times during a surgery, and each must be coupled and uncoupled from the sheath each time.
Prior art arthroscopes typically utilize a rotatable locking coupling collar on the sheath in order to couple the scope to the sheath. The collar has a lever-type handle protruding a significant distance and the coupling and uncoupling is accomplished by manually moving this handle within a range of approximately 45.degree.. Often the surgeon will bump the handle accidentally thereby partially or completely disconnecting the scope, resulting in distraction, delay, accidents and/or water leakage. A less obstrusive locking mechanism is, therefore, desirable. Additionally, this conventional coupling mechanism requires the surgeon to carefully align marks on the scope and sheath. Arthroscopic surgery demands extreme concentration viewing the operating area on a video screen while observing the manipulations of the surgical cutting instruments and any extra burden on the surgeon is undesirable. Consequently, an improved quick coupling and uncoupling device is highly desirable.
There are no known prior art quick coupling devices which overcome the foregoing disadvantages and which are suitable for arthroscopic coupling devices. Prior art quick couplings, used generally in the hydraulic and fluidic arts, are not suitable for arthroscopic purposes for a variety of reasons. First of all, known quick couplings are relatively bulky and unable to be sufficiently reduced in size to be suitable for arthroscopic applications. There appears to be a relationship between the diameters of the inside and outside of known couplings. There is a certain minimum inside diameter which is necessary to accomodate the plug member or whatever is to be received within the socket. There is also a certain minimum outside diameter necessary to accomodate the actuating components of quick couplings. The structure of known prior art couplings make the ratio of outside diameter to inside diameter unacceptably large for arthroscopic applications.
For example, U.S. Pat. No. 3,666,300 (Russell) shows a fluid line quick disconnect coupling. The coupling comprises a housing containing a plurality of annularly spaced locking pins and an outer actuating sleeve which is slidable on the housing in order to move the pins. Sliding the actuating sleeve forwardly causes the sleeve to engage an annular shoulder on each pin in order to move the pins radially outwardly to enable a nipple to be inserted into the socket. Sliding the sleeve rearwardly, after the nipple has been inserted, causes the sleeve to push against each pin to move it radially inwardly thereby locking the nipple in place. The structure of this device necessitates a relatively large diameter actuating sleeve. The sliding pins are fairly large and require large throughbores in the cylindrical housing thereby affecting the structural strength of the housing. In order to compensate for this loss of strength, the housing must be made large, resulting in a heavy, large diameter coupling device. Also, the particular design of the interacting surfaces on the actuating sleeve and the pins requires that the pins be of relatively large diameter which, in addition to requiring larger throughbores also makes the pins protrude radially outwardly a significant distance beyond the external surface of the cylindrical housing.
An additional disadvantage of this type of prior art quick coupling devices is that the plurality of annularly arranged locking pins generally used are retained within the socket by a separate member. In the Russell-type device this member is a split ring situated adjacent the radially inward end of the pins. The use of any such extra retaining members not only adds to cost and complexity but presents an additional component which could malfunction and, in the case of arthroscopic applications, any such malfunction may pose a serious safety hazard by enabling the pin or retaining member to fall into the patient.
Known arthroscopic sheaths are capable of being easily disassembled and it is, therefore, difficult for the surgeon to know if the device has been tampered with. This obviously creates a liability hazard for the surgeon. It would, therefore, be desirable to provide an arthroscopis sheath not easily disassembled without special tools.
Other known quick couplings, such as that shown in U.S. Pat. No. 3,188,123 (Hansen), require an interior actuating sleeve which is slidable relative to the housing and the nipple. Such designs require extra manufacturing steps to assure necessary close tolerances. It is impractical to reduce the size of these devices to that suitable for arthroscopic applications while simultaneously maintaining the critical tolerances necessary for arthroscopic purposes. Moreover, there are no known prior art quick couplings which are provided with a capability for accurately directly aligning the socket and plug members which are to be joined.
Accordingly, it is an object of the present invention to provide a quick coupling device suitable for arthroscopic purposes and capable of enabling quick, aligned connection and disconnection of a socket and associated plug member.
It is yet another object of this invention to provide a quick coupling device for joining a socket and plug member in a predetermined alignment. It is still a further object of this invention to provide a quick coupling device for so joining a socket and plug member without the need to have the user view either the socket or plug member.
It is additionally an object of this invention to provide a quick coupling device having a relatively small ratio of outside diameter to inside diameter, with minimum bulk and weight.
It is still another object of this invention to provide a quick coupling device utilizing a plurality of annularly spaced locking pins and having means for limiting the possibility that the integrity of the device may be compromised by disassembly by the user or that any part of the coupling device could fall into the interior of the device.
It is yet another object of this invention to provide an arthroscopic sheath which enhances the flow of irrigating fluid to or from the operating area.